The Data Reduction

There are many similarities between the reduction of single-beam dual-beam data. The basic differences are that each target exposure contains only a single image of the sky, instead of the two images produced by a dual-beam polarimeter, and that rotation between images is allowed. The various steps involved are summarised below. For more details go here. Details of how POLPACK can be used to implement these ideas in practice are given in later sections of this document.